html, body {
    margin: 0;
    width: 100%;
    height: 100%;
    overflow: hidden;
    background: #999;
}
.game-wrap {
    background: #cff;
    position: absolute;
    top: 20px;
    left: 20px;
    bottom: 20px;
    right: 20px;
}
.food {
    position: absolute;
    background-image: url(food_01.jpg);
}
.food.food-super {
    background-image: url(food_02.jpg);
}
.snake {
    border: 1px solid #f00;
    box-sizing: border-box;
    position: absolute;
    background: #000;
}
.snake-head {
    animation: blink 3s infinite;
}
@keyframes blink
{
    from {background-color: #000;}
    50% {background-color: #0f0;}
    to {background-color: #000;}
}